Electric heating attachment for electric fans



Nov. 13, 1934. L. LUDWIG 1,980,689

ELECTRIC HEATING ATTACHMENT FOR ELECTRIC FANS Filed April 8, 1933 Patented Nov. 13, 1934 UNITED STATES PATENT OFFICE ELECTRIC HEATING ATTACHMENT FOR ELECTRIC FANS 4 Claims.

The invention relates to electric heaters of a type which is attachable to electric fans. Its main object is to provide an efficient electric heater which can be attached to the guard of any portable, electric fan so that the currents of air passing through the heater will be heated by it. Another object is to provide the heater with means whereby its resistance element and the motor of the fan may be electrically connected in series parallel. A further object is to provide a heater of simple, neat and inexpensive construction which can be operated in connection with any electric fan without necessitating any alteration in any of its parts.

These and various other objects and advantages Will be readily understood from the following description and from the accompanying drawing of a preferred embodiment of the invention in which, however, Various modifications may be made without departing from the scope of the appended claims.

In the drawing:

Fig. l is a front elevation of the preferred embodiment of the heater 'shown with certain parts of the guard broken away;

Fig. 2 an enlarged, cross-sectional, side elevation of a special attachment plug used with the heater; and

Fig. 3 a side elevation of Fig. 1, taken on line 3 3 and shown partly in cross-section.

Referring now to all the views, simultaneously, the heater comprises a rod which is formed into a spiral and on which a plurality of supporting members 11 are strung in spaced relaof a coiled resistance wire.

its correct position, other supporting members 13, 14, 15 and 16 are employed for securing the rod and the resistance coil to the guard frame 17. This guard frame is provided with radial bars 18 which guard the front of the heater, and

with a plurality of hooks 19 which are constructed to hook on to the fan guard 20, a part of which is shown in Fig. 3. Each hook is provided with a sliding collar 21 which is pressed against the rod of the fan guard and held in place by a screw 22.

Asbestos-covered wires 23 and 24 are connected, respectively, to the inner and outer ends of the resistance element, while another asbestos-covered wire 25 is tapped into the element approximately halfway between its ends. These 60 three Wires are parts of a cable 26 which is supported in the member 16 and connected to the attachment plug 27, The construction of the attachment plug, which is plainly shown in Fig.

2, will now be described.

It consists oi" a housing 28 in which an insulating washer 29 is secured. A prong 30, which is made integral with a contact blade 31, is secured to the washer. Another prong 32 and another blade 33 are also secured to the washer, 70 but these are separate pieces and are insulated from each other by the washer. The Wire 23 connects the inner end of the resistance element with the screw 34 and, consequently, with both the prong and the blade 31. The wire 24 con- 75 nects the outer end of the resistance coil with a screw 35 associated with the prong 32, while the tap wire 25 connects the center of the coil with a screw 36 associated with the blade 33. The cable 26 passes through an opening 37 in 80 the tcp of the housing. An extra washer 38 is preferably inserted in the end of the housing to hide the wire connections. Two openings 39 and 40 are provided in the top of the housing through which the prongs of the attachment plug of the fan may be inserted to contact with the blades 3l and 33.

It will be seen that the construction of this attachment plug is such that, when the prongs 30 and 32 are connected to a source of electric 90 current and the prongs of the attachment plug of the fan are contacting with the blades 31 and 33, the resistance element and the fan motor will be connected in series parallel. To illustrate this: If the current enters through prong 32, it will flow through wire 24, resistance coil 12, tap wire 25, blade 33 and, through the fan motor circuit, back to blade 3l with its integral prong 30. At the same time a current will continue through the entire length of the resistance element and, through wire 23, back to the blade 31 and prong 30.

While I have shown the resistance element tapped about midway between its ends, it will be understood that it might be tapped at other points in order to increase or decrease the resistance in the fan motor circuit and accordingly change the speed of the fan. An extra resistance may also be inserted in the circuit to further decrease the speed of the fan.

Having described my invention and its operation, what I claim as new and wish to protect by Letters Patent is:

1. An electric heater of the class described, comprising a resistance element, a support f or said element, means for securing the heater to the front face of an electric fan, the resistance element connected by wires to an attachment plug having ,prongs for tapping ari-electric current, and means contained within said attachment plug whereby the attachment plug of 'the fan to which the heater is attached may be cahnected to the heater attachment plug in such a manner that the circuit of the velectric':lian--rnotor will be connected in series parallel with 'fthe-resistance element of the heater.

2. An electric heater of the class described, comprising a resistance element,v a -support for said element, means for securing the .heater to the front face of an electric fan, theresistance `element connected :by wires -to 4an .attachment plug Khaving prongs :for tapping an :electric vcnrrent', sand .means 'contained within said attachment :plug whereby ythe attachment plug of the :tanto which theheater is attached may be connected sto-the heater attachment plug in such a'manner `that the circuit of the electric fan -motor will be connected in series parallel with .a 4part ofthe resistance element.

3. An electric heater of the class described, comprising a spirally-.wound and spiral-shaped resistance element,y a spiral-shaped rod provided ,with ,insulating and heat resisting means for supporting said resisting element, the resistance element and the rod located within the convolutions of each other so as to lay in a common plane, a support for said rod, means for securing the heater to the front face of an electric fan, thev resistance element connected by Wires to an attachment plug having prongs for tapping an electric current, and means contained Within said attachment plug whereby the attachment plug ,o the vfan to which .the heater sattachedmay be connected Ato the heater attachment plug in such a manner that the circuit o'f the electric fan motor will be connected in :series parallel with a part of the resistance element of the heater.

electric lheater of the class described, comprising a spirally-wound and spiral-shaped resistance element, a spiral-shaped rod provided with insulating and heat resisting means for supporting said resisting element, the resistance element :and the rod located within the convolutions of each other so as to lay in a common iplanaagsupnortifer sacllrad, said support conzstituting a Aguard for ,the heater, lmeans for serurng the .heater to theiront face lof an/elec- :tric fan, Athe resistance element connected by wires :tc an attachment plus' having prongs for :tapping an v,electric current, and means contained within said attachment plug whereby the Vattachment plug of the fan to which the heater `is attached may be connected to the heater :attachment plug in such a manner that the cir- 

